As an analyzer which analyzes the amount of a component contained in a sample, there has been known an automated analyzer which measures a change in transmitted light intensity or scattered light intensity at a single wavelength or multiple wavelengths obtained by irradiating light from a light source onto a reaction solution obtained by mixing a sample with a reagent, and calculates the amount of a component based on the relationship between the light intensity and the concentration.
In the reaction of the reaction solution, there are roughly two types of analysis fields as follows: a colorimetric analysis using a color reaction between a substrate and an enzyme; and a homogeneous immunoassay using an agglutination reaction by binding between an antigen and an antibody. As the latter homogeneous immunoassay, measurement methods such as an immunonephelometric method and a latex agglutination method are known. Further, there is also known a heterogeneous immunoassay device which performs an immunoassay with higher sensitivity by employing a detection technique using chemiluminescence or electrochemical luminescence and a B/F separation technique.
In addition, there also exists an automated analyzer which measures blood coagulability. Blood maintains its fluidity in blood vessels and flows therethrough. However, once bleeding occurs, a coagulation factor present in plasma or platelets is activated in a chain reaction, and fibrinogen in plasma is converted into fibrin, and the fibrin is deposited, whereby bleeding is arrested.
Such blood coagulability includes an extrinsic one in which blood leaking outside the blood vessel coagulates and an intrinsic one in which blood coagulates in the blood vessel. The measurement items with respect to blood coagulability (blood coagulation time) include a prothrombin time (PT) in an extrinsic blood coagulation reaction test, an activated partial thromboplastin time (APTT) and a fibrinogen level (Fbg) in an intrinsic blood coagulation reaction test, and the like.
All these items are measured by detecting fibrin deposited by adding a reagent to start coagulation using an optical, physical, or electrical technique. As the method using an optical technique, there is known a method in which light is irradiated onto a reaction solution, and fibrin deposited in the reaction solution is detected as a change in the intensity of scattered light or transmitted light over time, whereby the time when fibrin starts to deposit is calculated. The coagulation time in a blood coagulation reaction (particularly, the item of Fbg) is as short as several seconds, and therefore, it is necessary to perform photometry at short intervals of about 0.1 seconds, and also when the reaction solution is coagulated, the reaction container cannot be recycled by cleaning, and therefore, the reaction is performed in an independent photometric port, and the reaction container is disposable. Further, the reaction time starts immediately, and therefore, many devices are configured such that stirring using a stirrer which is performed in the above-described colorimetric analysis, homogeneous immunoassay, or the like is not performed, but stirring is performed by a pressure generated when a sample or a reagent is discharged to effect the reaction, and a change in light intensity is measured. Further, it is essential for the automated analyzer to perform measurement with high reproducibility and high reliability. Accordingly, even in the case where the reaction solution is stirred by a discharge pressure, it is necessary to mix the entire reaction solution uniformly with good reproducibility and effect the reaction.
According to PTL 1, a reaction container is disposed in a holding member which performs conical rotational motion, and immediately after it is detected that a reagent is dispensed therein, the reaction container is rotated for each holding member, whereby the sample and the reagent are stirred. According to this method, a mechanism of rotating the reaction container is needed, and therefore, it is assumed that the number of components is increased, the structure is complicated, and the cost of the device is increased.
Also in PTL 2, a sample and a reagent are stirred by shaking a reaction container similarly. In this case, a pendulum motion, a reciprocating motion, an eccentric rotational motion, or a compound motion by combining two or more of these motions is performed. It is considered that in this case, stirring can be performed more uniformly with higher reproducibility than in (PTL 1) by a complicated motion, however, it cannot be denied that the structure is complicated for that.
In PTL 3, when a reagent is dispensed in a sample in a specimen container, suction and discharge of the sample are alternately repeated several times by a reagent dispensing probe at the time point when the reagent dispensing probe reached the liquid surface of the sample by employing the detection of the liquid surface, whereby the sample is stirred. It is considered that in this case, stirring can be presumably performed efficiently, however, the possibility of contamination of the reagent probe with the sample is high. Further, in the case of a device in which a specimen container or a reaction container is held in a rotary disk, it is necessary to perform the suction and discharge operations by stopping the rotation of the disk for a given time, and therefore, the processing ability may be decreased.